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Progenitor Mass Distribution of Core-Collapse Supernova Remnants in Our Galaxy and Magellanic Clouds based on Elemental Abundances

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 Added by Satoru Katsuda Dr.
 Publication date 2018
  fields Physics
and research's language is English




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We investigate a progenitor mass distribution of core-collapse supernova remnants (CCSNRs) in our Galaxy and the Large and Small Magellanic Clouds, for the first time. We count the number of CCSNRs in three mass ranges divided by the zero-age main-sequence mass, $M_{rm ZAMS}$; A: $M_{rm ZAMS} < 15 {rm M}_odot$, B: $15 {rm M}_odot < M_{rm ZAMS} < 22.5 {rm M}_odot$, C: $M_{rm ZAMS} > 22.5 {rm M}_odot$. Simple compilation of progenitor masses in the literature yields a progenitor mass distribution of $f_{rm A}: f_{rm B}: f_{rm C} =0.24:0.28:0.48$, where $f$ is the number fraction of the progenitors. The distribution is inconsistent with any standard initial mass functions. We notice, however, that previous mass estimates are subject to large systematic uncertainties because most of the relative abundances (X/Si) are not really good probe for the progenitor masses. Instead, we propose to rely only on the Fe/Si ratio which is sensitive to the CO core mass ($M_{rm COcore}$) and $M_{rm ZAMS}$. Comparing Fe/Si ratios in SNRs in the literature with the newest theoretical model, we estimate 33 $M_{rm COcore}$ and $M_{rm ZAMS}$, leading to a revised progenitor mass distribution of $f_{rm A}: f_{rm B}: f_{rm C} = 0.47: 0.32 : 0.21$. This is consistent with the standard Salpeter initial mass function. However, the relation between $M_{rm COcore}$ and $M_{rm ZAMS}$ could be affected by binary evolution, which is not taken into account in this study and should be considered in the future work to derive a better progenitor mass distribution estimate.



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275 - Carles Badenes , Dan Maoz , 2010
The physical sizes of supernova remnants (SNRs) in a number of nearby galaxies follow an approximately linear cumulative distribution, contrary to what is expected for decelerating shock fronts. This has been attributed to selection effects, or to a majority of SNRs propagating in free expansion, at constant velocity, into a tenuous ambient medium. We compile a list of 77 known SNRs in the Magellanic Clouds (MCs), and argue that they are a fairly complete record of the SNe that have exploded over the last ~20kyr, with most now in the adiabatic, Sedov phase of their expansions. The roughly linear cumulative size distribution (uniform in a differential distribution) can result from the combination of a deceleration during this phase, a transition to a radiation-loss-dominated phase at a radius that depends on the local gas density, and a distribution of ambient densities varying roughly as rho^{-1}. This explanation is supported by the observed -1 power-law distributions of three independent tracers of density: HI column density, Halpha surface brightness, and star formation rate from resolved stellar populations. In this picture, the observed cutoff at r~30 pc in the SNR size distribution is due to a minimum in the mean ambient gas density in the regions where supernovae (SNe) explode. We show that M33 has a SNR size distribution similar to that of the MCs, suggesting these features, and their explanation, may be universal. In a companion paper (Maoz & Badenes 2010), we use our sample of SNRs as an effective SN survey to calculate the SN rate and delay time distribution in the MCs. The hypothesis that most SNRs are in free expansion, rather than in the Sedov phase of their evolution, would result in SN rates that are in strong conflict with independent measurements, and with basic stellar evolution theory.
We infer the progenitor mass distribution for 22 historic core-collapse supernovae (CCSNe) using a Bayesian hierarchical model. For this inference, we use the local star formation histories to estimate the age for each supernova (SN). These star formation histories often show multiple bursts of star formation; our model assumes that one burst is associated with the SN progenitor and the others are random bursts of star formation. The primary inference is the progenitor age distribution. Due to the limited number of historic SNe and highly uncertain star formation at young ages, we restrict our inference to the slope of the age distribution and the maximum age for CCSNe. Using single-star evolutionary models, we transform the progenitor age distribution into a progenitor mass distribution. Under these assumptions, the minimum mass for CCSNe is ${M_textrm{min}}~=~8.60^{+0.37}_{-0.41} M_odot$ and the slope of the progenitor mass distribution is $alpha = -2.61^{+1.05}_{-1.18}$. The power-law slope for the progenitor mass distribution is consistent with the standard Salpeter initial mass function ($alpha = -2.35$). These values are consistent with previous estimates using precursor imaging and the age-dating technique, further confirming that using stellar populations around SN and supernova remnants is a reliable way to infer the progenitor masses.
The physics of core-collapse (CC) supernovae (SNe) and how the explosions depend on progenitor properties are central questions in astronomy. For only a handful of SNe, the progenitor star has been identified in pre-explosion images. Supernova remnants (SNRs), which are observed long after the original SN event, provide a unique opportunity to increase the number of progenitor measurements. Here, we systematically examine the stellar populations in the vicinities of 23 known SNRs in the Small Magellanic Cloud (SMC) using the star formation history (SFH) maps of Harris & Zaritsky (2004). We combine the results with constraints on the SNR metal abundances and environment from X-ray and optical observations. We find that 22 SNRs in the SMC have local SFHs and properties consistent with a CC explosion, several of which are likely to have been high-mass progenitors. This result supports recent theoretical findings that high-mass progenitors can produce successful explosions. We estimate the mass distribution of the CC progenitors and find that this distribution is similar to a Salpeter IMF (within the uncertainties), while this result is shallower than the mass distribution found in M31 and M33 by Jennings et al. (2014) and D{i}az-Rodr{i}guez et al. (2018) using a similar approach. Additionally, we find that a number of the SMC SNRs exhibit a burst of star formation between 50-200 Myr ago. As these sources are likely CC, this signature may be indicative of massive stars undergoing delayed CC as a consequence of binary interaction, rapid rotation, or low metallicity. In addition, the lack of Type Ia SNRs in the SMC is possibly a result of the short visibility times of these sources as they may fall below the sensitivity limits of current radio observations.
The material expelled by core-collapse supernova (SN) explosions absorbs X-rays from the central regions. We use SN models based on three-dimensional neutrino-driven explosions to estimate optical depths to the center of the explosion, compare different progenitor models, and investigate the effects of explosion asymmetries. The optical depths below 2 keV for progenitors with a remaining hydrogen envelope are expected to be high during the first century after the explosion due to photoabsorption. A typical optical depth is $100 t_4^{-2} E^{-2}$, where $t_4$ is the time since the explosion in units of 10 000 days (${sim}$27 years) and $E$ the energy in units of keV. Compton scattering dominates above 50 keV, but the scattering depth is lower and reaches unity already at ${sim}$1000 days at 1 MeV. The optical depths are approximately an order of magnitude lower for hydrogen-stripped progenitors. The metallicity of the SN ejecta is much higher than in the interstellar medium, which enhances photoabsorption and makes absorption edges stronger. These results are applicable to young SN remnants in general, but we explore the effects on observations of SN 1987A and the compact object in Cas A in detail. For SN 1987A, the absorption is high and the X-ray upper limits of ${sim}$100 Lsun on a compact object are approximately an order of magnitude less constraining than previous estimates using other absorption models. The details are presented in an accompanying paper. For the central compact object in Cas A, we find no significant effects of our more detailed absorption model on the inferred surface temperature.
The structure and morphology of supernova remnants (SNRs) reflect the properties of the parent supernovae (SNe) and the characteristics of the inhomogeneous environments through which the remnants expand. Linking the morphology of SNRs to anisotropies developed in their parent SNe can be essential to obtain key information on many aspects of the explosion processes associated with SNe. Nowadays, our capability to study the SN-SNR connection has been largely improved thanks to multi-dimensional models describing the long-term evolution from the SN to the SNR as well as to observational data of growing quality and quantity across the electromagnetic spectrum which allow to constrain the models. Here we used the numerical resources obtained in the framework of the Accordo Quadro INAF-CINECA (2017) together with a CINECA ISCRA Award N.HP10BARP6Y to describe the full evolution of a SNR from the core-collapse to the full-fledged SNR at the age of 2000 years. Our simulations were compared with observations of SNR Cassiopeia A (Cas A) at the age of $sim 350$~years. Thanks to these simulations we were able to link the physical, chemical and morphological properties of a SNR to the physical processes governing the complex phases of the SN explosion.
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